CN111994866A - Bending strain enhanced ultraviolet photoelectric position sensor and preparation method thereof - Google Patents

Abstract

An ultraviolet photoelectric position sensor with enhanced bending strain and a preparation method thereof belong to the field of photoelectric position sensors. The structure is a three-layer structure of a flexible substrate, a film and an electrode; the bottom layer is a flexible substrate layer and is made of fluorine crystal mica sheets; the intermediate layer is In doped with Cr₂O₃A thin film layer deposited on the flexible substrate; the upper layer is an electrode layer which is composed of two strip-shaped electrodes and is a reading electrode of photoelectric signals. The position of its spot can be discerned from the measured voltage or current. By mechanically bending the sample, the sensitivity of position detection can be significantly improved, thereby realizing an ultraviolet photoelectric position sensor enhanced by bending strain. The ultraviolet light potential provided by the inventionThe sensor has simple structure, high sensitivity and good transparency, and can directly detect without an additional amplifying circuit.

Description

A bending strain-enhanced ultraviolet photoelectric position sensor and preparation method thereof

technical field

The invention belongs to the field of photoelectric position sensors, in particular to an ultraviolet photoelectric position sensor with enhanced bending strain and a preparation method thereof.

Background technique

Photoelectric sensor realizes the conversion of optical signal and electrical signal through photoelectric conversion. It is one of the core devices of photoelectric conversion and has been used in various fields in modern industry and daily life. The photoelectric position sensor is a photoelectric sensor sensitive to the position of the incident light spot, and its output signal is related to the position of the light spot on the photosensitive surface. The photoelectric position sensor based on the semiconductor lateral photovoltaic effect is a photoelectric distance measuring device developed in the 1980s. It uses the lateral electric field generated by the lateral photovoltaic effect to realize the detection of the position of the incident light. High speed and high reliability.

Although photoelectric position sensors have been widely used, their sensitivity and linearity are crucial for the application of photoelectric position sensors, and exploring new materials and structures to enhance and improve the performance of photoelectric position sensors has received extensive attention . At the same time, with the reduction of the size of the basic components and the improvement of the multi-functional integration, the existing photoelectric sensors have gradually been unable to fully meet the application requirements. Especially for ultraviolet photoelectric position sensors, it is very important to improve the sensitivity, and some special fields also put forward application requirements for flexibility and visible light transparency.

SUMMARY OF THE INVENTION

In view of the above requirements, the present invention proposes an ultraviolet photoelectric position sensor with enhanced bending strain and a preparation method thereof.

A bending strain-enhanced ultraviolet photoelectric position sensor, as shown in Figure 1, consists of a three-layer structure of a flexible substrate, a film and an electrode; the bottom layer is the substrate layer of a flexible fluorocrystalline mica sheet, with a thickness of 5-50 μm; the middle layer is It is a Cr-doped In ₂ O ₃ thin film layer with a thickness of 0.02-1 μm and a mass fraction of Cr of 0.1-10%; the top layer is an electrode layer (the electrode layer is composed of elemental metal materials, metal alloy materials and conductive metal compounds. One or several kinds of electrodes), the electrode layer is composed of two strip electrodes with a thickness of 0.02-1 μm, which are read electrodes for photoelectric signals. The whole sensor has bending deformation, and its curvature is -10～+10% mm ^-1 .

Another aspect of the present invention provides a method for preparing an ultraviolet photoelectric position sensor with enhanced bending strain, the steps of which are as follows:

(1) Cleaning the flexible substrate;

Use acetone, ethanol and deionized water to ultrasonically clean the fluorine crystal mica sheet in sequence, or use a plasma cleaning machine to clean it, so that the surface of the fluorine crystal mica sheet is free from pollution;

(2) Cr-doped In ₂ O ₃ films were prepared by pulsed laser deposition;

Using pulsed laser deposition technology, Cr-doped In ₂ O ₃ was selected as the target material, and the Cr-doped In ₂ O ₃ film was deposited on the fluorocrystalline mica sheet in an oxygen environment;

(3) Thinning the flexible substrate layer;

Use mechanical peeling to thin the flexible mica layer to 5-50 μm;

(4) Preparation of electrodes;

Using vacuum coating, magnetron sputtering, laser deposition or screen printing methods, two electrodes are prepared on the Cr-doped In ₂ O ₃ film, and the two electrodes are connected to an external resistance measuring element to form a photoelectric position sensor;

(5) The bending sensor obtains an ultraviolet photoelectric position sensor with enhanced bending strain;

The sensor is mechanically bent to obtain an ultraviolet photoelectric position sensor with enhanced bending strain.

In the above step (2), the parameters used in the preparation of the thin film by the pulsed laser deposition technique are as follows: the distance between the Cr-doped In ₂ O ₃ target and the fluorocrystalline mica sheet is 40-70 mm, and the oxygen partial pressure in the cavity is 0.05-70 mm. 10Pa, the temperature of the fluorocrystalline mica sheet is 600-750°C, the frequency of the pulsed laser is 1-5Hz, and the deposition time is 0.1-2 hours.

Advantages of the present invention:

The invention adopts the common pulsed laser deposition growth method to deposit a Cr-doped In ₂ O ₃ film on a fluorine crystal mica sheet that can be purchased directly to prepare an electrode, and then bends the substrate mechanically to utilize the bending on the film. The flexoelectric effect produced by the strain enhances the sensitivity of position detection, thereby obtaining an ultraviolet photoelectric position sensor with enhanced bending strain. The ultraviolet photoelectric position sensor enhanced by bending strain has the advantages of simple structure, low manufacturing cost, simple operation and good application prospect. At the same time, since Cr-doped In ₂ O ₃ and fluorocrystalline mica are both transparent materials for visible light, if the electrode material is also made of transparent materials such as ITO, the entire sensor will have the excellent feature of being transparent to visible light.

Description of drawings

1 is a schematic structural diagram of the ultraviolet photoelectric position sensor enhanced by bending strain according to the present invention;

The names of each part are: 1 is fluorine crystal mica sheet, 2 is In ₂ O ₃ film doped with Cr, 3 is electrode;

Fig. 2 is the test chart of the photoelectric response signal of the ultraviolet photoelectric position sensor in the unbent state, when the light pulse is irradiated to different positions of the film;

Fig. 3 is a schematic diagram of the structure of the ultraviolet photoelectric position sensor generating compressive strain under "u" shape deformation;

Figure 4 is a test diagram of the photoelectric response signal of the ultraviolet photoelectric position sensor under the "u" shape deformation state, when the light pulse is irradiated to different positions of the film;

FIG. 5 is a schematic structural diagram of the ultraviolet photoelectric position sensor generating tensile strain under “n” type deformation;

Fig. 6 is a test chart of the photoelectric response signal of the ultraviolet photoelectric position sensor under the "n" type deformation state, when the light pulse is irradiated to different positions of the film.

Detailed ways

The implementation and characteristics of the technical solutions of the present invention are described in detail below in conjunction with specific embodiments to help readers understand the spirit and beneficial effects of the present invention, but cannot constitute any limitation to the implementable scope of the present invention.

Example 1

Step 1: Cleaning the flexible substrate.

The substrate is 10×2×0.2mm fluorocrystalline mica sheet, and acetone, ethanol and deionized water are alternately used for ultrasonic cleaning, so that the surface of the substrate is free from pollution.

Step 2: Cr-doped In ₂ O ₃ film was prepared by pulsed laser deposition.

The Cr-doped In ₂ O ₃ target material with a mass fraction of 5% was selected, and the Cr-doped In ₂ O ₃ film was deposited on the fluorine crystal mica substrate under the oxygen environment by using the pulsed laser deposition technology. The distance between the target and the fluorine crystal mica sheet is 50mm, the oxygen partial pressure in the cavity is 0.1Pa, the temperature of the fluorine crystal mica sheet is 600 ℃, the frequency of the pulse laser is 2Hz, and the deposition time is 20 minutes. The mica flakes were naturally cooled to room temperature.

Step 3: Thinning of the flexible substrate.

Use transparent glue and a knife to peel off the 0.2mm thick fluorocrystalline mica sheet along the cleavage plane and thin it to 0.02mm.

Step 4: Preparation of electrodes.

Two strip electrodes (electrode size 0.5 × 0.8 mm, electrode spacing 7 mm) were prepared on the Cr-doped In ₂ O ₃ film with conductive silver paste, and the two electrodes were connected to an external measuring element (Keithley 2400 digital source). surface).

Step 5: bending the sensor to obtain an ultraviolet photoelectric position sensor with enhanced bending strain;

Selecting organic glass with a certain curvature (-10～+10% mm ^-1 ), and fixing the sensor on the curved surface of the organic glass, the ultraviolet photoelectric position sensor with enhanced bending strain is obtained.

The prepared ultraviolet photoelectric position sensor is an ultraviolet photoelectric position sensor capable of realizing bending strain enhanced sensitivity. At room temperature, a fixed current is applied between the two electrodes. When the UV light illuminates different positions of the sensor, different voltages can be obtained. The voltage is linearly related to the position of the incident light. Changing the curvature of the sensor bend can enhance the sensitivity of position detection.

In the unbent state, different locations of the film were irradiated with a CW laser with a wavelength of 405 nm. The laser power is 60mw, the spot diameter is 2mm, the distance between the two electrodes is defined as L, the center of the electrodes is the origin of the x coordinate axis, and the position of the left electrode is x=-L/2, and the position of the right electrode is x= L/2, use an external test device (Keithley 2400 digital source meter) to measure the photoresistance value of the film. As shown in Figure 2, the position sensor exhibits linear position sensitivity characteristics.

When the sensor is bent in a "u" shape using plexiglass molds with different curvatures (as shown in Figure 3), the film develops compressive strain. The same laser is incident again at the positions of x=-L/2 and x=L/2, and the response signal is shown in Fig. 4 . With the larger "u" curvature of the sensor and the larger the compressive strain of the film, the absolute value of the photoresistance value at both the x=-L/2 and x=L/2 positions increases, at -7.69% ^mm- Under the curvature of ¹ , they are increased by 84.96% and 46.25% respectively, that is, the position-sensitive characteristic of the sensor has been enhanced.

When the sensor was bent in an "n" type using plexiglass molds with different curvatures (as shown in Figure 5), the film developed tensile strain. The same laser is incident again at the positions of x=-L/2 and x=L/2, and the response signal is shown in Fig. 6 . With the larger "n"-type curvature of the sensor and the larger tensile strain of the film, the absolute value of the photoresistance value at both x=-L/2 and x=L/2 positions increases, at 7.69% ^mm- Under the curvature of ¹ , they are increased by 67.29% and 48.76% respectively, that is, the position-sensitive characteristic of the sensor has been enhanced.

Claims (7)

1. a UV photoelectric position sensor with enhanced bending strain is characterized in that: it is composed of a three-layer structure of a flexible substrate, a film and an electrode; the bottom layer is a flexible substrate layer, and a fluorocrystal mica sheet is selected for use; the intermediate layer is deposited on a flexible substrate. The bottom layer is the Cr-doped In ₂ O ₃ film; the top layer is the electrode layer, which is composed of two strip electrodes, which are the reading electrodes of the photoelectric signal; position sensor. 2 . The ultraviolet photoelectric position sensor with enhanced bending strain according to claim 1 , wherein the electrode layer is made of one or more of simple metal materials, metal alloy materials or conductive metal compounds. 3 . 3 . The ultraviolet photoelectric position sensor with enhanced bending strain according to claim 1 , wherein the thickness of the electrode layer is 0.1 to 100 μm, the thickness of the fluorocrystalline mica substrate is 5 to 50 μm, and the thickness of the Cr-doped The thickness of the In ₂ O ₃ film is 0.02 to 1 μm. 4 . The ultraviolet photoelectric position sensor with enhanced bending strain according to claim 1 , wherein: in the Cr-doped In ₂ O ₃ film, the mass fraction of Cr is 0.1% to 10%. 5 . 5 . The ultraviolet photoelectric position sensor with enhanced bending strain according to claim 1 , wherein the sensor has bending deformation, and its curvature is -10-+10% mm ^-1 . 6 . 6. the preparation method of a kind of bending strain-enhanced ultraviolet photoelectric position sensor as claimed in claim 1, its steps are as follows: (1) Cleaning the flexible substrate; Use acetone, ethanol and deionized water to ultrasonically clean the fluorine crystal mica sheet in sequence, or use a plasma cleaning machine to clean it, so that the surface of the fluorine crystal mica sheet is free from pollution; (2) Cr-doped In ₂ O ₃ films were prepared by pulsed laser deposition; Using pulsed laser deposition technology, Cr-doped In ₂ O ₃ was selected as the target material, and the Cr-doped In ₂ O ₃ film was deposited on the fluorocrystalline mica sheet in an oxygen environment; (3) Thinning the flexible substrate layer; Use mechanical peeling to thin the flexible mica layer to 5-50 μm; (4) Preparation of electrodes; Using vacuum coating, magnetron sputtering, laser deposition or screen printing methods, two electrodes are prepared on the Cr-doped In ₂ O ₃ film, and the two electrodes are connected to an external resistance measuring element to form a photoelectric position sensor; (5) The bending sensor obtains an ultraviolet photoelectric position sensor with enhanced bending strain; The sensor is mechanically bent to obtain an ultraviolet photoelectric position sensor with enhanced bending strain. 7 . The method for preparing an ultraviolet photoelectric position sensor with enhanced bending strain according to claim 6 , wherein in the pulsed laser deposition, the distance between the Cr-doped In ₂ O ₃ target and the fluorocrystalline mica sheet is 7 . 40～70mm, the oxygen partial pressure in the cavity is 0.05～10Pa, the temperature of the fluorocrystalline mica sheet is 600～750℃, the frequency of the pulsed laser is 1～5Hz, and the deposition time is 0.1～2 hours.

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